Lens Actuator Corner-Coil Layout for Large-Aperture Camera Modules
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Solution Overview
Problem
Conventional voice coil motor (VCM) technology is difficult to apply to micro-scale camera modules requiring low power consumption, and there is a need for smaller, larger-diameter actuators capable of mounting large-aperture lenses for high-resolution cellular phone cameras with autofocus, shutter shaking prevention, and zooming functions.
Innovation Solution
A lens moving apparatus with a cover member, housing, bobbin, and coils, featuring a first magnet on the housing corner and a second coil between the magnet and the cover member's side plate, allowing movement perpendicular to the optical axis, reducing height and enabling large-aperture lens mounting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional VCM technology is used, then the actuator can drive the lens, but the height in the optical-axis direction is large and it cannot accommodate large-aperture lenses
Solution Approach 1:
The patent repositions the OIS coil from a conventional location to the corner portion of the housing, utilizing the lateral dimension rather than the optical-axis dimension. This dimensional shift allows the coil to be arranged in a plane perpendicular to the optical axis, thereby reducing the height requirement in the optical-axis direction while maintaining OIS functionality.
Solution Approach 2:
The actuator is divided into functionally independent sections: the first coil and first magnet for autofocus (vertical movement), and the second coil and second magnet for optical image stabilization (horizontal movement). This segmentation allows each subsystem to be optimized independently, with the OIS subsystem using lateral space rather than consuming optical-axis height.
2Volume of moving object
If the camera module is scaled down to micro-scale, then the overall size is reduced, but conventional VCM technology becomes difficult to apply and power consumption increases
Solution Approach 1:
By positioning the OIS coil in the corner portion and arranging it to extend in directions perpendicular to the optical axis, the design efficiently utilizes lateral space in the scaled-down module. This avoids the need for vertically stacked arrangements that would increase height and potentially require more complex, power-intensive actuation mechanisms.
Solution Approach 2:
The corner portion housing structure serves multiple functions: it provides structural support, defines the lateral boundaries for the OIS coil movement, and integrates both autofocus and OIS functionalities within a compact footprint. This multi-functional design reduces the need for additional components that would increase power consumption in micro-scale modules.
3Ease of operation
If the second coil is positioned to face the second surface of the first magnet, then OIS function is achieved, but the area of the second surface is smaller than the area of the first surface
Solution Approach 1:
The magnet is designed with non-uniform surface areas: the first surface (facing the first coil for autofocus) has a larger area to provide sufficient magnetic flux for vertical actuation, while the second surface (facing the second coil for OIS) has a smaller area adequate for lateral stabilization. This local differentiation optimizes each function for its specific requirements without wasting space.
Solution Approach 2:
The OIS function is achieved by utilizing the lateral dimension (perpendicular to optical axis) rather than increasing the optical-axis dimension. The second coil is arranged to extend in directions perpendicular to the optical axis, allowing effective OIS operation with a smaller magnet surface area since the coil can wrap around or extend laterally to compensate for the reduced surface area.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces the optical-axis direction height and allows for the mounting of large-aperture lenses, enhancing autofocus and zooming capabilities in micro-scale camera modules.
Implementation Method 1
a second coil disposed between the second side surface and the side plate of the cover member so as to face the second side surface of the first magnet, the second coil being configured to move the housing in a direction perpendicular to an optical axis using interaction with the first magnet
Implementation Method 2
a first coil disposed on the bobbin... a first magnet disposed on the corner portion of the housing... an area of the second surface is smaller than an area of the first surface
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
An embodiment comprises: a housing including side portions and corner portions; a bobbin arranged in the housing; a first coil arranged on the bobbin; first magnets which are arranged in the corner portions of the housing and have first sides facing the first coil, and second sides opposite to the first sides; and second coils which are arranged to face the second sides of the first magnets and move the housing in a direction perpendicular to the optical axis by interaction with the first magnets.